Fan or impeller



B. SCHMELZER FAN on IMPELLER May 27 'Filed Aug. 9 1922 A TTORNE YPatented May 27, 1924.

UNITED. STATES BRUNO SCHMELZER, or JERSEY our, NEW JEitSEY. 2

FAN on IMPELITER/ Application filed August 9, 1922. Serial no. 580,785

To all whom it may concern:

Be it known that I, BRUNo SGHMELZER, a citizen of Poland, and residentof Jersey City, in the county of Hudson and State of New Jersey, haveinventeda certain new and useful Fan or Impeller, of which the followingis a specification, the same being a full, clear, and exact descriptionof the invention, such as will enable others skilled in the art to whichit appertains to make and use the same.

The invention which constitutes the sub ject matterof this applicationrelates to improvements in centrifugal fans, compressors, air and gaspumps, fan blowers, andother kindred apparatuses which are hereinafterdesignated as-fans; and its has for its object the provision of animproved construction of that type of fan wherein a .flow of air, wateror other fluid (hereinafter referred to as air) is discharged from thefan wheel.

Another object of, the invention is to increase the efficiency of suchfans and to eliminate the noise ordinarily incident to the operationthereof.

In many centrifugal fans where the air is taken in axially anddischarged circumferentially the current which is discharged from thebackor disk portion of the blades has a tendency to cross over towardthe intake end and to re-enter the lnterior of the fan centripetally,and I have therefore de signed my fan so that the fluid that passesbeing to aconsiderable extent a re-circulation back from the dischargeside, whereby by my invention the air entering centripetally through theinner end of the blades and passing axially between or along the same isdischarged centrifugally from the outer portion of the blades withoutany objectionable re-circulation thereof, thus enabling the fan tooperate with a maximum efficiency and without undue noise.

The noise produced by high speed centrifugal fans is also ordinarilycaused by the fluid being forced to pass over sharp edges whereupon itceases to flowsmoothly and becomes broken .up into whirls or eddies thusforming a turbulent mass.

the rear edges of the blades where the air is drawn inby. suction andconcaving the anterior face of said blades an unobstructed channel forthe even andsteady movement] By o d ofthe fluid is provided, therebyavoiding the setting up of any sharp edges to interfere in anymanner'with the smooth passage of the current. 7

Another source ,7 of excessive'noise insuch fans is the formation ofthin blasts of air passing laterally' by the fan blades and between thesame and the casing, which blasts conflict with the normal centrifugalflow of the current and produce eddies and vortices in the air movementand cause backpressure.

"Again, interstices between the fan wheel and the casing,orirregularities in the inner face of the latter, serve in many fans toconstitute pockets in which air is compressed by the centrifugal currentand, on account of the tendency of such air cushions to expand againstthe said current, friction is created which develops a harsh and severenoise. fan wheel made with truncated cone shape side portions whichconform in contour with the casing will eliminate the above:

named disadvantages. I

' Wlth the above considerations in mind and witha view of overcoming theobjections pointedout, I have devised the fan illustrated in theaccompanying drawings, in" -'which' 1 FigureQ is a transverse section ofthe same. I p A As 'one'example or embodiment of the invention I haveillustrated the same as applied to a radial flow fan in which the fluidoperated upon enters axially and centrally in the inlet and isdischarged circumferentially at the outlet of the casing or housing. Thefan wheel comprises a disk or back plate or wall 3forming a convexdeflector 3 and a shroud, ring, annulus or forward wall 4, intermediateof which are positioned a-plurality of im peller blades 5.

The fan wheel comprises approximately radial spokes or arms Qcarried bya shaft 2 which works in a casing 1. The back plate 3 and shroud 4t andouter portions of the said arms are preferably of cone-shaped contour,

'the fan wh eel thus comprising truncated coneshaped side portions.Th'eflblades are consequently made with preferably outwardly convergingedges. The inner portion of the shroud terminates in a-flat horizontalThe interior face' of the casing is preferably so formed as tocorrespond with the said contour of the fan wheel both in longitudinaland cross section through any blade, and the side wall or head 1; of thecasing at the intake end of the blades ispreferably detachable and madewith an inlet tube 1 projecting into and beyond the said ring l.

The inner ends 5' of the blades project forwardly so that the air whendrawn in by suction will not strike a sharp edge, and the impellerblades are preferably ofsubstantially radial position, and the anteriortaces'of the same as well as the outer portions ofc the arms2"arepreterably concavedasat 5? so as t aif a moo h n e y pa g o the current,although thesame maybe'ot different inclinatien, curvature or thicknessWithoutd nartius fre n hen incipl Qfmy V invention which is applicableto 7 othertypes 'are contained in the recessed portions or pocketsordinarily present in fan casings or of blades! he fluid nte ins the intke" cadet t n p s sb y e. po nte end theshat 2 formlng c 1i6a e ete raadf s car ied o n e we th has pl e er' disk M 9 v shroud and dischargedwithout striking. or impinging upon adverse air currents such-asrhousings-or meeting any obstruction'or opposing element whatever andalso without having any chanceto enter the intake again and tore-circulate. wheel the air is guided from theintake side to the centreof the casing trom'which it is peripherally discharged in'a strongandeven.

flow of current On account of the air enteringwithin the plane of theadjacentside of the fan wheel,

' and crossing a-portion of the interior edges of the blades by the useof the tubular inlet 1 there is no obstruction of the fluid ,in itsnormal axial progress within-the boundary of the fan as the arms 2' donot interfere with strengthenedby the outer ends of the arms.

2* which, together withthe' blades are concaved whereby great stiffnessand rigidity. are attained. Theouter portions of-the disk; and shroudand also'the' casing extendinwardly in cone-shaped contourto theenteredge of the bladeslto: correspond;With-the:

- converging edges of the blad s, Byrreasonof the circumferentialchannel of; =t-he casing f being narrowed near its outer portion-sofasto be of the same width as the-exterior? edges;

' of the blades acontractedchannel continuing.

of the same diminished width to the outlet 7' By my conical fan of thecasing is formed and consequently a concentrated blast is secured, whileat the same time on account of my peculiar con- 7 struction of partsthere are no air cavities in my device to set up friction against thecur-V rent flow or to cause any of the said air current tobecome chokedbackward at any point of the movement of the fluid. 7

I wish to have it understood. that I do not desire to be limited tothe-particular use or theexact details of construction shown anddescribed, for obvious modifications will oc eur to persons skilled inthe art. VVha't I claimas myinventioncisi 7 1 In a device of the classdescribed, a ca-s- 111g compr sing unobstructed inlet and outlet openmouths, afan wheel having a fan shaft with a single set of-spokeslyingin-thecentral plane of the wheel and provided with concave bladessupported thereby, theffan Wheel having an open channel therethrough atandbetween the inner edges-fof'the blades of substantially the diameterof thein'let wherein the airgfe'nteringaxially is ;ca used tograduallyrotate circumferentially before being acted upon in saidchannel by the Wheel to avoid ,ainpock'et resista11cc,the said bladeshavinginner edges adapted to" cut the;

surrounding air edgewise with wedging action, in the path d'ftravel, thecasing lying sutliciently near the sides otthe'wheel as to prevent backpressure orjsluct ion resistance therebetween to avoidfharsh noises.

from emanating. from the fan},

2. ln adevice of the clss described,

casing. comprising; unobstructed inlet and outlet open mouths, av fanwheel having a tan shaft with a, singleset of spokes lying in thecentral plane of thewheel'and provided V with concave bladessupportedthereby; the fan- Wheel having an open channel therethrough atand between the inner edges, of

the blades of substantially the diameter of the inlet wherein the airentering axially is-caused t-o gradually rotate circumferentiallywbeforebeing acted upon in said channelby the: spokes-to avoidlair-pzocketresistance, the said blades having forwardly,

curved inner edges adapted tojcut the surrounding air edgewise'with awedging'action in the path of travel, the'casing lying tfiei nt y nearhe si es. of t e hee as to prevent back pressure or suction 'resi stance therebetween to avoid harsh noises fr memanat ngf m th fa In adevice/oi the class described, a

casing eompr-ising inlet and outlet open mouths, a;;f;an wheel having afan'shaft and provided ith on a e blade Supp r h re n, he n h l; ha ingnpe ha nel-"therethrough at and between the inner ge c the bla es q -s sbn a y h d me; ndt he, inlet where n. he a r.e ri

axially is; caused to; gradually rotate cir eumferentially bysuction toavoid aiapoca the adjacent parts of the casing lying close to andparallel therewith the entire extent of said edges, the shroudterminating in a ring concentric with the inlet and the latterprojecting into the said open channel, the

ring and open channel being substantially of the same diameter.

4. In a device of the class described, a casing comprising inlet andoutlet open mouths, a fan wheel having a fan shaft and provided withconcave blades supported therein, the fan wheel having an open channeltherethrough at and between the inner edges of the blades ofsubstantially the diameter of the inlet wherein the air entering axiallyis caused to gradually rotate circumferentially by suction to avoidair-pocket resistance, the said blades having inner edges adapted to cutthe surrounding air edgewise with a wedging action in the path oftravel, the casing lying sufficiently near the sides of the wheel as toprevent back pressure or suction resistance therebetween to avoid harshnoises from emanating from the fan, the blades of the fan wheel beingpositioned intermediate a disk and shroud and having outwardlyconverging edges, and the adjacent parts of the casing lying close toand parallel therewith the entire extent of said edges, the end of thefan shaft carrying a conical deflector and the disk having a c0nvexportion rotating within the said open channel to provide deflectingmeans of larger diameter to create an increased flow of air thereat,said convex portion conforming to the contour of the adjacent part ofthe casing.

5. In a device of the class described, a casing comprising unobstructedinlet and outlet open mouths, a fan wheel having a fan shaft andprovided wit-h concave blades supported. thereby, the fan wheel ,havingan open channel therethrough at and between. the inner edges of theblades of substantially the diameter of the inlet wherein the airentering axially is caused to gradually rotate circumferentially beforebeing acted upon in said channel by the wheel to avoid air-pocketresistance, the said blades having inner edges adapted to cut thesurrounding air edgewise with a wedging action in the path of travel,the casing lying sufliciently near the sides of the wheel as to preventback pressure or suction resistance therebetween to avoid harsh noisesfrom emanating from the fan, the blades of the fan wheel beingpositioned intermediate a disk and shroud and having outwardlyconverging edges, and the adjacent parts of the casing lying close toand parallel therewith the entire extent of said edges, the outletchannel of the casing being eccentric with respect to the fan wheel andof the width of the narrow outer edges of the blades and continuing ofthe said contract/ed width to the mouth thereof and being narrowest justabove the said mouth.

- Signed at New York in the county of New York and State of New Yorkthis 23rd day of June A. D. 1922.

BRUNO SC HMELZER.

